well its not just bolt on, the bumper is pretty close but there is a little lip on the upper left and right corner of it that wont match up with your fender.. I think you could have a bodyshop do some fiberglass work or bend your origional fender to match the bumper.. im not sure, but im going through the same problem right now.

well i dont just have a bumper, i have a hood, headilghts, and fenders.. this is what i have decided.. Take the new 01 fenders and cut the wheel well flare off and attach to old fender, then procede with fender flare to meet up with bumper, but then also gonna have to flare out the bumper so it doesnt look 2 weird.

Um.... that seems like a lot of work to just have a M3 look bumper... Especially since it's a OEM M3 bumper... the brackets will not align correctly, and flaring the fenders... you're tapping into a whole new ball game.. you need to flare the back fenders as well... and just change that 325 into a "M3-look" completely.. OEM M3 rear bumper as well... it's going to look weird when your front fenders are larger than your rears.